In order to provide higher-speed uplink and downlink packet services and improve the utilization efficiency of frequency spectra, 3GPP (3rd Generation Partnership Project) has introduced high speed downlink packet access (shortened as HSDPA) and high speed uplink packet access (shortened as HSUPA) features in specifications for TD-SCDMA systems, and has reduced the network processing time delay by introducing adaptive modulation and coding (shortened as AMC), hybrid automatic repeat request (shortened as HARQ) and a Node B control scheduling technique, thereby having improved the speed of uplink/downlink packet services and the utilization efficiency of frequency spectra.
In HSDPA and HSUPA technologies, an MAC-hs sub-layer and an MAC-e sub-layer as well as relevant entities have been introduced into a media access control (shortened as MAC) layer, respectively. On the network side, the MAC-hs sub-layer, MAC-e sub-layer and relevant entities are all located in the Node B. The MAC-hs sub-layer, MAC-e sub-layer and entities not only accomplish uplink/downlink data processing functions, but also are responsible for management and scheduling of related wireless physical channel resources in the HSDPA and HSUPA technologies.
In the HSDPA technology of TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) systems, wireless physical channel resources newly introduced include: high speed physical downlink shared channels (shortened as HS-PDSCH), shared control channels for HS-DSCH (shortened as HS-SCCH) and shared information channels for HS-DSCH (shortened as HS-SICH). Wherein, the HS-PDSCH is used to carry user’ service data, the HS-SCCH is used to carry related control information of controlling a UE (User Equipment) to receive the HS-PDSCH, and the HS-SICH is used to carry feedback information that the UE sends to the Node B, indicating that the HS-PDSCH and user service data have been received by the UE. In the HSDPA technology, the transmit time interval (shortened as TTI) of the HS-SCCH, the HS-PDSCH and the HS-SICH is all 5 ms, FIG. 1 is a schematic diagram illustrating the timing relationship among the HS-SCCH, HS-PDSCH and HS-SICH in the HSDPA technology in the TD-SCDMA system based on related technologies; as shown in FIG. 1, wherein, the signaling channels HS-SCCH and HS-SICH which are used for scheduling and controlling are configured with one-to-one correspondence and are used in pairs.
FIG. 2 is a schematic diagram illustrating the structure of data field information carried by the HS-SCCH, which, as shown in FIG. 2, specifically contains the following control information: an HARQ Process ID, which takes 3 bits; redundance version (RV) information, which takes 3 bits; a new data indicator (shortened as NDI), which takes 1 bit; an HS-SCCH cyclic sequence number (HCSN), which takes 3 bits; a UE ID (CRC—cyclic redundancy check), which takes 16 bits; a modulation format indicator (MF), which takes 1 bit; transport block size information (shortened as TBS), which takes 6 bits; the channelized code set information, which takes 8 bits; and time slot position information, which takes 5 bits.
In the HSUPA technology of the TD-SCDMA system, regarding the physical layer, the HSUPA technology has newly introduced E-DCH physical uplink channels (shortened as E-PUCH) to carry user service data, wherein, the E-DCH is an enhanced dedicated channel. In the HSUPA technology, the E-PUCH can be differentiated into scheduling and non-scheduling E-PUCHs. A radio network controller (shortened as RNC) allocates the non-scheduling E-PUCH channel resources, and as long as such resources are available, the UE can transmit the channels at any time. For the scheduling E-PUCH channel resources, they are allocated dynamically by the MAC-e sub-layer and entity in the Node B according to the UE's request. At the same time, downlink E-DCH absolute grant channels (shortened as E-AGCH) and uplink E-DCH hybrid ARQ indicator channels (shortened as E-HICH) have also been newly introduced. The E-AGCH is used to carry related control information that the Node B grants the scheduling E-PUCH to the UE to send, while the E-HICH is used to carry receipt acknowledgement indication information of the user service data on the E-PUCH channel that the Node B sends to the UE. FIG. 3 is a schematic diagram illustrating the timing relationship among the E-AGCH, E-PUCH and E-HICH channels in the HSDPA technology in the TD-SCDMA system based on related technologies, as shown in FIG. 3, the transmit time interval (TTI) of the E-AGCH, the E-PUCH and the E-HICH is all 5 ms.
FIG. 4 is a schematic diagram illustrating the structure of data field information carried by the E-AGCH, which, as shown in FIG. 4, contains the following control information: an absolute grant (power) value (AGV), code resource information (CRRI), time slot resource information (TRRI), an E-AGCH cyclic sequence number (ECSN), a resource durability indicator (RDI), an E-HICH indicator (EI), an E-UCCH (Enhanced Uplink Control Channel) number indicator (ENI) and a UE ID (CRC cyclic redundancy check).
In the HSDPA technology, if the service being transmitted is a real-time service (such as a VoIP service, i.e. IP telephony), then one method is allowing the Node B, through the HS-SCCH, to allocate the HS-PDSCH resources either long-lasting continuously or periodically dynamically to transmit service data to the UE; the disadvantage of this method is that the overheads of the control channels HS-SCCH and HS-SICH are large, and such a disadvantage becomes even more significant especially for those services with a relatively low traffic. Another improved method is using an HS-SCCH-less technology, i.e. simplifying control parameters during the HSDPA transmission process, such as fixing or preconfiguring some parameters, preallocating some HS-PDSCH physical channel resources and combining a blind detection technique, so that it is not necessary to send the HS-SCCH during the first HARQ transmission of data packets of this type of services, i.e. the HS-PDSCH channel resources granted by the HS-SCCH is not sent during transmission of new packets, but the preallocated HS-PDSCH channel resources and parameters are used for transmitting new packets. In such a method, firstly the RNC or the Node B preallocates the HS-PDSCH channel resources, and then sends them to the UE through an upper layer signaling. The disadvantage of this method is that the signaling time delay is quite significant during reconfiguration of the preallocated HS-PDSCH channel resources, without being able to offer dynamic reconfiguration.
In the HSUPA technology, if the service being transmitted is a real-time service (such as a VoIP service), then one method is allowing the Node B, through the E-AGCH, to allocate the scheduling E-PUCH resources either long-lasting continuously or periodically dynamically to transmit service data to the UE; the disadvantage of this method is that the overhead of the control channel E-AGCH is large, and such a disadvantage becomes even more significant especially for those services with a relatively low traffic, moreover, it is also difficult to ensure real-time services. Another method is performing the first HARQ transmission of packets through a non-scheduling approach, while performing the HARQ retransmission of packets through a scheduling approach. In such a method, it is the RNC that allocates the non-scheduling E-PUCH resources according to existing technologies, and then sends them to the Node B and the UE, respectively, through an upper layer signaling. The disadvantage of this method is also that the signaling time delay is quite significant during reconfiguration of the non-scheduling E-PUCH resources, without being able to offer dynamic reconfiguration.
It can be seen from the above descriptions that whether for the HSDPA technology or the HSUPA technology, during the performance of resource allocation of the real-time service transmission, there is a problem of the high control channel overhead, the long signaling time delay during reconfiguration of the preallocated channel resources, and the inability to offer dynamic reconfiguration.